PDUMPFS(8)

NAME
pdumpfs - A daily backup system similar to Plan9's dumpfs

SYNOPSIS
pdumpfs src-dir dest-dir [dest-basename]

DESCRIPTION
pdumpfs is a simple daily backup system written in Ruby (ruby(1)), which is similar to Plan9's dumpfs that preserves every daily snapshot.

Back up your home directory with pdumpfs, and you can retrieve any past day's snapshot of any file.

pdumpfs constructs each day's snapshot in the directory named YYYY/MM/DD under the destination directory. All source files are copied to the snapshot directory for the first time, and on and after the second time, pdumpfs copies only updated or newly created files and stores unchanged files as hard links to the files of the previous day's snapshot to save disk space.

The latest version of pdumpfs is always available at http://namazu.org/~satoru/pdumpfs/.

EXAMPLE
To backup your home directory /home/yourname to /backup, run the following command.

    pdumpfs /home/yourname /backup >/backup/log 2>/backup/error-log

On and after the second day, it is a good idea to invoke the backup command with cron(8) daemon. Adding the following line to your crontab file allows you to back up your home directory at 5 a.m. everyday.

    00 05 * * * pdumpfs /home/yourname /backup >/backup/log 2>/backup/error-log

If the backup system works well, you can retrieve any given day's file with a file name like /backup/2001/02/19/yourname/...

LIMITATION
-   pdumpfs can only handle normal files, directories, and symbolic links.

-   pdumpfs may not work on systems other than UNIX because pdumpfs utilizes hard links.

-   pdumpfs is not suited for a directory containing large files which are updated frequently.

-   If more than 31 day absence occurs, incremental backup would not be performed. So, back up your files on a daily basis.

-   With pdumpfs, you can safely remove unnecessary files because the past files can be retrieved at any time. However, you must not rely too much on pdumpfs. It may have serious bugs.

TIPS

-   If the total disk usage increases by 10 MB everyday, about 4 GB disk space will be consumed every year. It would not matter so much considering the recent evolution of computer resources.

-   Back up your files to a physically separated device.

-   On some systems, files can be made immutable.

    To make all files in /backup immutable on Linux, run the following command as root:

        chattr -R +i /backup

    On 4.4BSD derived systems, run the following command as root:

        chflags -R schg /backup

    These commands will keep you from accidentally removing your backup files with rm -rf.

AUTHOR
pdumpfs and the HTML document were written by Satoru Takabayashi <satoru@namazu.org>.

This manual page was translated from the HTML document by Hiroyuki Shimada <shimaden@din.or.jp>, and reformatted by Akinori MUSHA <knu@iDaemons.org>.

SEE ALSO
chattr(1), chflags(1), crontab(5), cron(8)